> ## Documentation Index > Fetch the complete documentation index at: https://docs.activeviam.com/llms.txt > Use this file to discover all available pages before exploring further. # Commodity curvature risk position down > The Commodity Curvature Risk Position Down (K_b-) in FRTBCombinedCube, the bucket-level curvature capital requirement under the downward scenario per Basel MAR21.5 [sbm](../tags/sbm) | | | | ------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | **Description** | The bucket level capital requirement under the downward scenario | | **Variations** | [high-low](./high-low) | | **Hierarchies required in the view** | [Commodity Buckets](./commodity-buckets) | | **Reference** | [\[MAR21.5\]](https://www.bis.org/basel_framework/chapter/MAR/21.htm?inforce=20230101\&published=20200327#paragraph_MAR_21_20230101_21_5) | | **Notation** | $K_b^{-}$ | | **Formula** | $\displaystyle K_{b}^{-} =\sqrt{max\left(0,\sum _{k\in b} max(CVR_k^{-},0)^{2} +\sum _{k\in b}\sum _{l\in b, l\neq k}\rho_{kl}\cdot CVR_k^{-} \cdot CVR_l^{-} \cdot \psi(CVR_k^{-},CVR_l^{-})\right)}$ |